GaAs substrates and InP substrates have been used as substrates used for semiconductor light emitting elements and semiconductor electronic devices (see, for example, patent document 1). On the other hand, in recent years, semiconductor light emitting elements and semiconductor electronic devices using substrates such as GaN substrates having a threading dislocation density much higher than those of GaAs and InP substrates have been made and put to practical use. For example, as such devices, semiconductor lasers and light emitting diodes using III-V group nitride compound semiconductors and capable of light emission from a blue region to an ultraviolet region are known.    Patent Document 1: Japanese Patent Laid-Open No. 6-37386